Apparatus for making precision holes in a web

ABSTRACT

A heated gas lamina flow web perforating apparatus including a tubing assembly and a mechanism for moving a web past the tubing assembly, means for heating the tubing assembly and a gas supply source which supplies surges of gas through the tubing assembly whereby the lamina gas flow is heated and is directed against the passing web so that precision holes are formed therein.

United States Patent [191 1111 3,805,649 Hester Apr. 23, 1974 [5 APPARATUS FOR MAKING PRECISION 1,747,087 2/1930 Schmalz 83/177 HOLES IN A WEB 3,212,378 10/1965 Rice 83/53 [75] Inventor: Benny Lee Hester, Winston-Salem,

Primary Examiner-W1llie G. Abercrombie Attorney, Agent, or Firm-Grover M. Myers [73] Assignee: R. J. Reynolds Tobacco Company,

Winston-Salem, NC.

22 Filed: Nov. 6, 1972 ABSTRACT [21] Appl. No.: 304,181 A heated gas lamina flow web perforating apparatus including a tubing assembly and a mechanism for moving a web past the tubing assembly, means for (gl. 83lll's7gaf8gjgg heafing the tubing assembly and gas supply Source [58] Fie'ld "833/177 53 which supplies surges of gas through the tubing assembly whereby the lamina gas flow is heated and is di- [56] References Cited rected against the passing web so that precision holes are formed therein. UNITED STATES PATENTS 3,227,019 6/1966 Schur 83/177 X 8 Claims, 7 Drawing Figures :2 Tl lVlE 1; F l 44 PRESSURIZED I GAS t 26 lO\ I i 5 3O 36 D l6 5 OWER 34* 0 SOURCE A as 11 '52 1 L 58 1 I( i 7* I l l/ q -*-iiil A MTENTED APR 2 3 I974 SHEET 2 BF 3 FATENTEUAPRZIi I974 3.805649 SHEET 3 BF 3 .00 L/ Q U FIGY APPARATUS FOR MAKING PRECISION HOLES IN A WEB BACKGROUND OF THE INVENTION This invention relates to an apparatus and method for perforating a web and, in particular, an apparatus for making holes in a film by utilizing heated lamina flow.

In recent years, it has been discovered that a cigarette filters efficiency can be increased if the smoke drawn through the cigarette impinges against the filter plug at a high velocity. The impingement of the smoke on the plug causes more particles to be removed from the smoke taken in by the smoker. Because of this phenomenon, the industry has tried to develop ways to increase the velocity of the smoke stream when the cigarette is being smoked without altering the draft or draw characteristics of the cigarette. One approach has been to direct the smoke stream through a plurality of small holes in that the velocity of the smoke stream will be increased prior to its contacting the filter plug.

it has also been found, however, that unless the holes which are used are precisely formed and of a uniform size, the proper velocity of the smoke stream and draft characteristics of a cigarette cannot be attained. If all of the holes are too large, the velocity of the smoke stream exiting the holes will be too low, thereby reducing the force with which the smoke impinges against the filter plug, which will reduce the efficiency of the filter. Even if only one hole is too large, the volume of flow through that hole will increase in such a manner as to reduce the velocity through the large hole as well as the remaining holes. This reduction in velocity will again reduce the efficiency of the filter. On the other hand, if the holes utilized are too small, the draft characteristics of the cigarette will be adversely affected.

Therefore, it is necessary to produce a plurality of precisionally made holes in order to take advantage of the impingement filtering principle.

One filter configuration which was constructed includes a filter plug having a circumferential groove which is surrounded by a non-absorbent film, such as mylar. The mylar contains a plurality of radial holes therethrough into which the smoke stream is directed. The smoke stream can be channeled on the outside of the plug by various means prior to directing the stream through the holes in the film and impinging the smoke stream on the plug. The purpose for positioning the holes radially or circumferentially was twofold: First, it allowed the greatest number of holes to be utilized, thus increasing the efficiency of the filter; and secondly, if the holes were spaced longitudinally along the filter plug, some holes would be near the smokers mouth, producing the possibility that some of the collected particles might get to the smoke in the mouth. The non-absorbent mylar film was used to eliminate the wicking problem; however, because of the physical properties of mylar, none of the standard methods of making holes could be adapted for commercial use, primarily because of the high speed production of today's cigarette making machines. It is, therefore, necessary for the apparatus used for making the holes in the mylar to be capable of producing 2,000 groups of transverse holes in the mylar web per minute.

A number of presently known methods have been tried but each had its drawback. A mechanical punching operation was tried, but the most efficient hole size is .0010 inch and it is difficult to make the punches this small and maintain the proper tolerance of iOOOl inches. The punches also wore out after only a few groups of holes had been made.

An electrical sparking technique was tried but it was discovered that it was difficult to control where the holes would be made due to the dielectric properties of the mylar. When using the electrical sparking technique, it was hard to make the holes in the web at the proper location two times in succession; thus the repeatability of the sparking technique was inadequate. On some occasions, the web will not be perforated because the spark jumps completely around the mylar web from one electrode to the other because of the dielectric properties of the mylar.

A third conventional method which was experimented with uses heated needles to perforate the web, but it was discovered that the mylar stuck to the needles as they were extracted from the web, thereby stringing out the mylar. I

Still another technique which was tried was to pass the film over a heated drum containing a plurality of openings and draw a vacuum in the drum, thus pulling holes in the mylar. This method was unsuccessful because the openings in the drum had to be of such small size that they became plugged by the mylar which was drawn through them.

Finally, lasers were tried; however, the energy required for the amount of work which the laser did was disproportionate to other methods. Also, to be of commercial value, a plurality of holes had to be made in a web; therefore, a plurality of lasers would be required or a sophisticated optical system to split a single beam and focus each portion of a split beam down to the proper size would have to be constructed. Since the apparatus is to be used in an industrial environment, the extra safety precaution would be necessary if a laser were utilized. It can be seen from the discussion above that there presently exists an urgent need for an apparatusv which can make a plurality of precision holes in a web to produce an element suitable for use in an impingement type filter which will overcome the disadvantages of the prior art.

SUMMARY OF THE INVENTION It is, therefore, an object of this invention to provide an apparatus which will produce a plurality of precision holes in a film.

Another object of this invention is to provide an apparatus which uses a hot gas stream to produce precision holes in a web.

Still another object of this invention is to provide an apparatus which can be used to make a row of precision holes in an intermittently moving web which are transverse to the direction of movement of the web.

- Still another object of this invention is to provide an apparatus having a plurality of heated nozzles which will heat surges of compressed gas passing therethrough and direct the hot gas onto a web so that a plu rality of precision holes are formed in the web.

Still another object of this invention is to provide an apparatus which will produce a plurality of precision holes in a webof non-absorbent material so that the web can be used to regulate the velocity of cigarette smoke impinging on a filter plug as the cigarette is being smoked.

The tubes communicate with a gas supply which regulates the pressure of the gas supplied to the heating tubes, and a timer is used to open and close a valve at a preselected time to control the quantity of pressurized gas supplied to the tubes. The heated columns of gas produced by the tubes impinge against the web and form precision holes therein.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and additional objects, features and advantages of the invention will be apparent to those skilled in the art from the following detailed description of a preferred embodiment and with the accompanying drawings, in which:

FIG. I is a diagrammatic illustration of a heated lamina flow web perforating apparatus according to the present invention;

FIG. 2 is an enlarged plan view of a section of a web illustrating the configuration of the aperture made by the apparatus according to the present invention;

FIG. 3 is a cross section view of section of the web as taken on line 3-3 of FIG. 2;

FIG. 4 is a perspective view of a web perforating device in which the frame carries a plurality of tubular heating elements; and

FIGS. 5, 6 and 7 are diagrammatic illustrations of a portion of a heated lamina flow web perforating apparatus used in conjunction with various types of web moving devices.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring more-particularly to the drawings, in FIG.

.1, numeral 10 indicates a heated lamina flow web perforating apparatus having a frame, tube or needle assembly 12 which is connected to a pressurized gas source 14 and a power source 16. A web 18 of a nonabsorbent film, such as mylar, is passed adjacent the frame portion 12 of the web perforator. The frame portion 12 includes upper and lower bars 20 and 22 made of a suitable conductive material, such as copper, brass, or the like. The bars are separated by and secured to an insulator block 24 of suitable material which is positioned between the bars at their corresponding rear edges. Terminals 26 and 28 on upper and lower bars 20 and 22, respectively, are connected to power sources 16 by electrical wires 30 and 32. The power source supplies a voltage of between .4 and volts to the tube assembly 12 with a current of between 2 to 25 amperes. These voltage and current values will vary and depend on the type of webwhich is to be perforated.

A heating tube or needle 34 is carried near the forward edge'of the bars 20 and 22 and extends through bores 36 and 38 in the bars. The upper end of the tubing '34 which extends through bar 20 is connected to a supply line 40 by a coupling 42. The tube should be made of a material such as stainless steel which is conductive but which has enough resistance to cause the tube to be heated. Suitable insulators are used to insulate the tube 34 from the supply line 40 to prevent the supply line 40 from carrying an electrical charge. The heating tube 34 communicates with the pressurized gas supply through supply line 40, solenoid valve 43 and line 44. Solenoid valve 43 is used to regulate the surges or pulses of pressurized gas which are supplied to the heating tube 34. The opening and closing of the solenoid 4 is controlled by an electrical timer 46 or other suitable means, such as a fluidic circuit or a mechanical linkage slaved to a web feeding apparatus. Any suitable gas can be used in the system, such as air, carbon dioxide, etc.

The lower end of the heating tube 34 extends through the lower bar 22 and the lower end or tip 48 of the tube is contiguous to the surface of the web 18. The distance between the tip and the web will, of course, dependon the characteristics of the web and the temperature of the lamina flow. As mentioned above, if the perforated,

web is to be used in an impingement type cigarette filter, preferably the size of the'holes should be .010 inches in diameter with tolerance of .0001 inches; therefore, the inside diameter A of the heating tube should be within the range of .009 to .0101 inches. A loop 50 in a heating tube 34 takes up any increase in length of the tube due to heat expansion.

Turning now to the operation of the apparatus, the power supply is activated and continuously supplies electrical current to the frame, thus the tube 34 is heated to a predetermined level depending on the gas temperature which is required for a particular type of webbing. When using the mylar film, it has been found that the temperature of the gas should be approximately 600 F. In this preferred embodiment, the movement of the web 18 is intermittent so that the web will stop beneath the tip 48 of the tube 34 at preselected times. As the web 18 is stopped beneath the tube, the timer 46 operates a solenoid valve 43 for a short duration so that the pressurized gas will flow through the tube 34 and impinge against the web 18.

When using a mylar film, it has been found that a time duration of approximately 5 milliseconds is required.

As the heated lamina flow 52 impinges against the web 18, the stream will initially produce a cavity 54 (see FIGS. 1 and 3) in the web and push the material from the cavity into an annular ridge or lip 56. A small hole at the center of the cavity is initially formed and gradually increasesin size until the diameter A of the hole 58 in the web corresponds to the inside diameter A of the heating tube 34. When the 5 millisecond time interval has elapsed, the timer 46 closes the solenoid valve 43 to interrupt pressurized gas flow to the Web 34 and the web 18 is moved a predetermined distance.

Although FIG. 1 illustrates the heated lamina web perforating apparatus as having a single tube, in a normal commercial application, the frame or tube assembly will include a plurality of tubes 62 as illustrated in FIG. 4. The tubes 62 are carried between conductive upper and lower plates 64 and 66. The plates 64 and 66 are spaced by and secured to insulator posts 68 and 68' (not shown). The lower end of the tube 62 extends through pIate 66 with their tips 70 positoned contiguous to the upper surface of a web 72. A manifold or cover 74 is secured to the top plate 64 and communicates with a pressurized gas source (not shown) through conduit 76. The manifold should be made of an insulative material which will not conduct heat or current. Terminals 78 and 78(not shown), carried on plates 64 and 66, respectively, are connected to the power supply (not shown) by electrical cables 80 and 80'. It should be understood that the tubes can be arranged in any pattern desired; for example, a diamond, star, diagonal line, etc.; and the cross sectional configuration of each tube can be of various geometric designs, such as a square, rectangle, etc.

In FIG. 5, the tube assembly is positioned adjacent to a web movement device 82. A web 84 is carried on a supply reel 86 and passes over a support roller 88 positioned contiguous to the tube assembly 10 and onto a take-up reel 90. The support roller 88 has a plurality of circumferentially spaced transverse grooves 92 in its peripheral surface. A geneva intermittent motion gear 94 is used to impart intermittent motion to the web 84. The geneva gear is so designed that each groove 92 on the surface of the roller 88 will stop at a point beneath the tips of the heating tubes in the tube assembly. The opening and closing of the solenoid valve (not shown) which supplies the gas to the heating tubes can be controlled by a timer as mentioned above or it can be slaved to the geneva gear by suitable mechanical linkage.

Another device which can be used to control the motion of the web is illustrated in FIG. 6. A supply roll reel 96 carries a web supply 98 which passes between aligning or guide rolls 100 and around a spacing roller 102 onto a dancing roller system including an idler roller 104, a reciprocating dancer roller 106 and a second roller roller 108. The web is then wound on a take-up reel 110. The tubing assembly 10 is positioned contiguous to the surface of the web 98 and is operated in the same manner as described hereinabove. The take-up reel 110 is continuously operated, but by reciprocating the dancer roller 106 upwardly, the web will stop beneath the tube assembly 10 until the slack has been taken out of the web'between the two idler rollers 104 and 108, thus the web can be stopped intermittently.

A final modified configuration of the heated lamina perforating apparatus is illustrated in FIG. 7. The web moving device has a supply reel 1 12 carrying a webbing supply 114. A pair of idler rollers 116 and 118 which are positioned adjacent to a tubing assembly 10 support the web 114 as it passes the assembly 10. The web 114 is wound around a take-up reel 120 which is operated at an extremely slow speed. Since the heated lamina flow is only applied to the web for approximately 5 milliseconds, the speed of the take-up roller 120 can be such that at any given time it would appear that the web is motionless at the time the lamina flow is applied to the web. This type of web moving device would produce a relatively slow apparatus and might be unsuitable for commercial use.

It can be seen from the above description and drawings that the heated lamina flow web perforator unit of the present invention provides an apparatus which will produce precision holes in a film as the film is moving intermittently past the perforating device.

The above-described embodiment can be modified in numerous ways, which will be apparent from the foregoing; for example, any suitable web moving mechanism may be utilized as well as any type of timing device which will permit surges or pulses of fluid to be applied to the web. However, these and other variations and changes can be made in the above invention as above described and illustrated without departing from the true spirit and scope thereof, as defined in the following claims.

I claim:

1. An apparatus for making precision holes in a web by directing a heated gas against said web comprising:

a. nozzle means for heating said gas and controlling the shape and dimensions of a stream of said gas directed against said web; and

b. means for supporting said web adjacent said nozzle means.

2. The apparatus of claim 1, further including means for supplying surges of pressurized gas to said nozzle means. 4

3. The apparatus of claim 2, wherein said means for supplying surges of pressurized gas includes:

a. a pressurized gas source;

b. conduit connecting said gas source to said nozzle means;

0. valve means in said conduit for regulating the flow of gas from the gas source to said nozzle means; and

d. means for selective opening and closing said valve means so that surges of pressurized gas are supplied to ,said nozzle means.

4. The apparatus of claim 2, wherein said nozzle means includes:

a. at least one tube having one end communicating with said means for supplying surges of pressurized gas and having, its other end disposed contiguous said web, said tube controlling the shape and size of streams of pressurized gas which are produced by said surges, said streams exiting said tube and impinging against said web; and

b. means for applying a predetermined current to said tube so that the streams of pressurized gas exiting said tube will be heated to a selected level.

5. The apparatus of claim 4, further including means for imparting intermittent motion to said web.

6. The apparatus of claim 1, wherein said nozzle means includes: 7

a. at least one tube having one end communicating with a pressurized gas source and having its other end disposed contiguous to said web, said tube controlling the shape and size of a streamof pressurized gas exiting said tube and impinging against said web; and

b. means for applying a predetermined current to said tube so that said pressurized gas exiting said tube will be heated to a selected level. I

7. The apparatus of claim 1, wherein said means for supporting said web further includes means for moving said web past said nozzle means.

8. The apparatus of claim 1, further including means for imparting intermittent motion to said web. 

1. An apparatus for making precision holes in a web by directing a heated gas against said web comprising: a. nozzle means for heating said gas and controlling the shape and dimensions of a stream of said gas directed against said web; and b. means for supporting said web adjacent said nozzle means.
 2. The apparatus of claim 1, further including means for supplying surges of pressurized gas to said nozzle means.
 3. The apparatus of claim 2, wherein said means for supplying surges of pressurized gas includes: a. a pressurized gas source; b. conduit connecting said gas source to said nozzle means; c. valve means in said conduit for regulating the flow of gas from the gas source to said nozzle means; and d. means for selective opening and closing said valve means so that surges of pressurized gas are supplied to said nozzle means.
 4. The apparatus of claim 2, wherein said nozzle means includes: a. at least one tube having one end communicating with said means for supplying surges of pressurized gas and having its other end disposed contiguous said web, said tube controlling the shape and size of streams of pressurized gas which are produced by said surges, said streams exiting said tube and impinging against said web; and b. means for applying a predetermined current to said tube so that the streams of pressurized gas exiting said tube will be heated to a selected level.
 5. The apparatus of claim 4, further including means for imparting intermittent motion to said web.
 6. The apparatus of claim 1, wherein said nozzle means includes: a. at least one tube having one end communicating with a pressurized gas source and having its other end disposed contiguous to said web, said tube controlling the shape and size of a stream of pressurized gas exiting said tube and impinging against said web; and b. means for applying a predetermined current tO said tube so that said pressurized gas exiting said tube will be heated to a selected level.
 7. The apparatus of claim 1, wherein said means for supporting said web further includes means for moving said web past said nozzle means.
 8. The apparatus of claim 1, further including means for imparting intermittent motion to said web. 